Confocal displacement sensor

Abstract

Optical axes of lens units of measurement heads are adjusted so as to be parallel to each other. The lens unit includes a diffraction lens. When adjusting the optical axis, in a state where the measurement heads face each other with a reference member interposed therebetween, light having a plurality of wavelengths are emitted from the measurement heads to one surface and the other surface of the reference member, respectively. Intensities of primary light having one wavelength, which are reflected by one surface and the other surface of the reference member respectively, and incident on the measurement heads through each of a path of a multi-order light having other wavelengths are displayed on a main display unit as information indicating a degree of orthogonality of the optical axes of the measurement heads with respect to the one surface and the other surface of the reference member.

What is claimed is: 
     
       1. A confocal displacement sensor comprising:
 a light projecting unit which emits light having a plurality of wavelengths; 
 a first head unit which includes a first confocal optical system having a first diffraction lens, generating chromatic aberration along an optical axis direction in the light emitted by the light projecting unit, and converging the light on a first surface of a measurement object; 
 a first spectroscope which divides a first light by each wavelength, the first light having been reflected by the first surface and having passed through the first confocal optical system; 
 a first light receiving unit which receives the divided first light for each wavelength and acquires an intensity of the light for each wavelength; and 
 a control device which is configured to be able to adjust an optical axis of the first head unit using a reference member having the first surface, 
 wherein the first head unit is configured such that a first primary light having one wavelength, which is emitted to the first surface through the first head unit, is reflected by the first surface and passes the first confocal optical system through a path of a first multi-order light having the one wavelength when the optical axis of the first head unit is orthogonal to the first surface, and 
 wherein the control device includes an intensity information display control unit causing a display unit to display, when adjusting the optical axis, as first intensity information, information on an intensity of a first determination light acquired from the first primary light having been reflected by the first surface and having passed the first confocal optical system through the path of the first multi-order light from among the intensities of the lights that the first light receiving unit receives, in a state where the reference member is disposed on a light emitting side of the first head unit. 
 
     
     
       2. The confocal displacement sensor according to  claim 1 , wherein the control device includes a posture adjustment image display control unit which causes the display unit to display, when the intensity information display control unit displays the first intensity information during adjusting the optical axis, a first posture adjustment image prompting an operation for adjusting a posture of the first head unit with respect to the reference member. 
     
     
       3. The confocal displacement sensor according to  claim 1 , wherein the first intensity information indicates a temporal change in an intensity of the first determination light. 
     
     
       4. The confocal displacement sensor according to  claim 1 , wherein the control device includes a display control unit causing a display unit to display a guidance screen to prompt an operation for adjusting a distance between the first head unit and the reference member and a posture of the first head unit with respect to the reference member in this order. 
     
     
       5. A confocal displacement sensor capable of measuring a thickness of a measurement object having first and second surfaces on opposite sides, the confocal displacement sensor comprising:
 a light projecting unit which emits light having a plurality of wavelengths; 
 a first head unit which includes a first confocal optical system having a first diffraction lens, generating chromatic aberration along an optical axis direction in the light emitted by the light projecting unit, and converging the light on the first surface of the measurement object; 
 a second head unit which includes a second confocal optical system having a second diffraction lens, generating chromatic aberration along an optical axis direction in the light emitted by the light projecting unit, and converging the light on the second surface of the measurement object; 
 a first spectroscope which divides a first light by each wavelength, the first light having been reflected by the first surface and having passed through the first confocal optical system; 
 a first light receiving unit which receives the divided first light for each wavelength and acquires an intensity of the light for each wavelength; and 
 a control device which is configured to be able to adjust an optical axis of the first head unit using a reference member having the first and second surfaces parallel to each other instead of the measurement object, 
 wherein the first head unit is configured such that a first primary light having one wavelength, which is emitted to the first surface through the first head unit, is reflected by the first surface and passes the first confocal optical system through a path of a first multi-order light having the one wavelength when the optical axis of the first head unit is orthogonal to the first surface, 
 wherein the second head unit is configured such that a second primary light having one wavelength, which is emitted to the second surface through the second head unit, is reflected by the second surface and passes the second confocal optical system through a path of a second multi-order light having the one wavelength when the optical axis of the second head unit is orthogonal to the second surface, and 
 wherein the control device includes an intensity information display control unit causing a display unit to display, when adjusting the optical axis, as first intensity information, information on an intensity of a first determination light acquired from the first primary light having been reflected by the first surface and having passed the first confocal optical system through the path of the first multi-order light from among the intensities of the lights that the first light receiving unit receives, in a state where the reference member is disposed between the first head unit and the second head unit. 
 
     
     
       6. The confocal displacement sensor according to  claim 5 , further comprising:
 a second spectroscope which divides the second light by each wavelength, the second light having been reflected by the second surface and having passed through the second confocal optical system; and 
 a second light receiving unit which receives the divided second lights for each wavelength and acquires an intensity of the light for each wavelength, 
 wherein the control device is configured to be able to further adjust the optical axis of the second head unit using the reference member, and 
 wherein the intensity information display control unit causes the display unit to further display, when adjusting the optical axis, as second intensity information, information on an intensity of a second determination light acquired from the second primary light having been reflected by the second surface and having passed the second confocal optical system through the path of the second multi-order light from among intensities of the lights that the second light receiving unit receives, in a state where the reference member is disposed between the first head unit and the second head unit. 
 
     
     
       7. The confocal displacement sensor according to  claim 6 ,
 wherein the first intensity information indicates a temporal change in an intensity of the first determination light, and 
 wherein the second intensity information indicates a temporal change in an intensity of the second determination light. 
 
     
     
       8. The confocal displacement sensor according to  claim 7 ,
 wherein the control device further includes a maximum intensity display control unit that causes the display unit to display first maximum intensity information indicating a maximum intensity by a present point in time in the temporal change of the intensity of the first determination light, and causes the display unit to display second maximum intensity information indicating a maximum intensity by the present point in time in the temporal change of the intensity of the second determination light. 
 
     
     
       9. The confocal displacement sensor according to  claim 7 ,
 wherein a peak wavelength of the first determination light changes according to a distance between the first surface and the first head unit, and a peak wavelength of the second determination light changes according to a distance between the second surface and the second head unit, and 
 wherein the control device further includes a range display control unit which controls the display unit to display a waveform of the first determination light on a wavelength axis, to change a position of the waveform of the first determination light on the wavelength axis according to a change in the distance between the first surface and the first head unit, and to display a range of the wavelength of the first determination light on the wavelength axis as a first wavelength range when the distance between the first surface and the first head unit is within a predetermined first distance range, and controls the display unit to display a waveform of the second determination light on the wavelength axis, to change a position of the waveform of the second determination light on the wavelength axis according to a change in the distance between the second surface and the second head unit, and to display a range of the wavelength of the second determination light on the wavelength axis as a second wavelength range when the distance between the second surface and the second head unit is within a predetermined second distance range. 
 
     
     
       10. The confocal displacement sensor according to  claim 7 ,
 wherein the first and second light receiving units acquire at least one of an intensity of the light emitted from the first confocal optical system of the first head unit and incident on the second confocal optical system of the second head unit and an intensity of the light emitted from the second confocal optical system of the second head unit and incident on the first confocal optical system of the first head unit in a state where the reference member does not exist between the first and second head units, and 
 wherein the control device further includes a aligning degree display control unit that causes the display unit to display aligning degree information indicating a aligning degree of optical axes of the first and second head units based on the at least one of the intensities acquired by the first and second light receiving units. 
 
     
     
       11. The confocal displacement sensor according to  claim 10 ,
 wherein the control device further includes
 a distance adjustment image display control unit which causes the display unit to display, when adjusting the optical axis, a first distance adjustment image prompting an operation for adjusting a distance between the first head unit and the reference member, and a second distance adjustment image prompting an operation for adjusting a distance between the second head unit and the reference member, 
 a posture adjustment image display control unit which causes the display unit to display, when adjusting the optical axis, a first posture adjustment image prompting an operation for adjusting a posture of the first head unit with respect to the reference member, and a second posture adjustment image prompting an operation for adjusting a posture of the second head unit with respect to the reference member, after the display unit displays the first and second distance adjustment images, and 
 an axis adjustment image display control unit which causes the display unit to display, when adjusting the optical axis, an axis adjustment image prompting an operation for aligning the optical axes of the first and second head units by moving at least one of the first and second head units, after the display unit displays the first and second posture adjustment images. 
 
 
     
     
       12. The confocal displacement sensor according to  claim 11 , further comprising:
 a first operation unit operated by a user to instruct display of the first and second distance adjustment images; 
 a second operation unit operated by the user to instruct display of the first and second posture adjustment images after displaying the first and second wavelength ranges by the range display control unit; and 
 a third operation unit operated by the user to instruct display of the axis adjustment images after displaying the first and second intensity information by the intensity information display control unit. 
 
     
     
       13. The confocal displacement sensor according to  claim 10 ,
 wherein the light projecting unit includes
 a first light projecting unit which emits a light to the first confocal optical system, and 
 a second light projecting unit which emits a light to the second confocal optical system, and 
 
 wherein the control device further includes
 a light control unit which performs at least one of a first control for controlling emission of the light in the first light projecting unit based on a light receiving signal output from the second light receiving unit and a second control for controlling emission of the light in the second light projecting unit based on a light receiving signal output from the first light receiving unit when the aligning degree display control unit displays the aligning degree information. 
 
 
     
     
       14. The confocal displacement sensor according to  claim 5 ,
 wherein the intensity information display control unit displays the first and second intensity information simultaneously on a single screen of the display unit. 
 
     
     
       15. The confocal displacement sensor according to  claim 5 ,
 wherein the confocal displacement sensor uses the light incident from one head unit of the first head unit and the second head unit to the other head unit to adjust the optical axis of the other head unit in a state where the first head unit and the second head unit are disposed to face each other. 
 
     
     
       16. The confocal displacement sensor according to  claim 5 , wherein the control device includes a posture adjustment image display control unit which causes the display unit to display, when the intensity information display control unit displays the first intensity information during adjusting the optical axis, a first posture adjustment image prompting an operation for adjusting a posture of the first head unit with respect to the reference member. 
     
     
       17. The confocal displacement sensor according to  claim 5 , wherein the control device includes a display control unit causing a display unit to display a guidance screen to prompt an operation for adjusting a distance between the first head unit and the reference member and a posture of the first head unit with respect to the reference member in this order. 
     
     
       18. A confocal displacement sensor capable of measuring a thickness of a measurement object having first and second surfaces on opposite sides, the confocal displacement sensor comprising:
 a light projecting unit which emits a plurality of light having a plurality of wavelengths; 
 first and second head units; 
 a first optical member provided in the first head unit, having a diffraction lens for generating chromatic aberration along an optical axis direction in the plurality of light emitted by the light projecting unit, and converging the plurality of light having chromatic aberration to emit each of the plurality of light to the first surface of the measurement object; 
 a first pinhole member provided in the first head unit and having a plurality of first pinholes through which a plurality of light, which have been focused and reflected by the first surface, passes as a plurality of first lights from among the plurality of light emitted to the first surface by the first optical member; 
 a second optical member provided in the second head unit, having a diffraction lens for generating chromatic aberration along the optical axis direction in the plurality of light emitted by the light projecting unit, and converging the plurality of light having chromatic aberration to emit each of the plurality of light to the second surface of the measurement object; 
 a second pinhole member provided in the second head unit and having a plurality of second pinholes through which a plurality of light, which have been focused and reflected by the second surface, passes as a plurality of second light from among the plurality of light emitted the second surface by the second optical member; 
 an acquisition unit which acquires intensities of the plurality of first light having passed through the plurality of first pinholes for each wavelength and acquires intensities of the plurality of second light having passed through the plurality of second pinholes for each wavelength; 
 a thickness calculation unit which calculates a thickness between the first surface and the second surface of the measurement object based on the intensities of the plurality of first and second light for each wavelength acquired by the acquisition unit; and 
 a control device which is configured to be able to adjust optical axes of the first and second optical members using a reference member having the first and second surfaces parallel to each other instead of the measurement object, 
 wherein the first head unit is configured such that a first primary light having one wavelength, which is emitted to the first surface through the first optical member, is reflected by the first surface and passes the first pinhole through a path of a first multi-order light having the one wavelength when an optical axis of the first optical member is orthogonal to the first surface, 
 wherein the second head unit is configured such that a second primary light having one wavelength, which is emitted to the second surface through the second optical member, is reflected by the second surface and passes the second pinhole through a path of a second multi-order light having the one wavelength when an optical axis of the second optical member is orthogonal to the second surface, and 
 wherein the control device includes an intensity information display control unit, when adjusting the optical axis, causing a display unit to display, as first intensity information, information on an intensity of a first determination light acquired from the first primary light having been reflected by the first surface and having passed the first pinhole through the path of the first multi-order light from among the intensities of the plurality of light that the acquisition unit acquires, and to display as second intensity information, information on an intensity of a second determination light acquired from the second primary light having been reflected by the second surface and having passed the second pinhole through the path of the second multi-order light from among the intensities of the plurality of light that the acquisition unit acquires, in a state where the reference member is disposed between the first head unit and the second head unit. 
 
     
     
       19. The confocal displacement sensor according to  claim 18 ,
 wherein the first intensity information is a value based on a difference between a maximum intensity value and a minimum intensity value among a plurality of intensities of a plurality of first determination light corresponding to the first head unit, and 
 wherein the second intensity information is a value based on a difference between a maximum intensity value and a minimum intensity value among a plurality of intensities of a plurality of second determination light corresponding to the second head unit. 
 
     
     
       20. The confocal displacement sensor according to  claim 18 ,
 wherein the confocal displacement sensor has a measurement mode for measuring the measurement object and an optical axis adjustment mode for adjusting the optical axis of the head unit.